Etching methods, methods of removing portions of material, and methods of forming silicon nitride spacers

摘要

A processing method includes patterning a material over a semiconductive substrate having a center and an edge. The method includes forming a layer of first material against a second material and over the semiconductive substrate and first etching the first material in a reaction chamber. First etching provides a first center-to-edge uniformity across the wafer surface and a first selectivity for the first material relative to the second material. The method also includes second etching the first material to provide a second center-to-edge uniformity across the wafer surface and a second selectivity greater than the first selectivity for the first material relative to the second material. The second center-to-edge uniformity is less than the first center-to-edge uniformity. The method also includes cleaning a component of the first material from at least one sidewall of the reaction chamber between the first and second etchings.